ABUJA, May 14  -- At least 11 people were feared dead in a suicide bomb attack near a military base in Nigeria's northeastern state of Borno on Wednesday, a military source said Thursday, less than 24 hours after the incident.

The suicide attack, by a female member of Boko Haram, heralded an attempted invasion of Maiduguri, capital of the northern Borno State, by the terror group, according to the military source, who was among troops deployed to repel the attack at dusk on Wednesday.

Youth vigilante group members and Nigerian soldiers were among those feared dead, the source said, adding a heavy shooting followed the explosion. Residents said they heard explosions and deafening sounds from high caliber weapons before security operatives arrived and cordoned off the area late Wednesday.

While fleeing as Nigerian forces tried hard to repel the attack, the Boko Haram members used their female fighters as shield, leaving some of them behind as they fled from the battlefield, said another security source not authorized to speak to the media on the development.